Colon cancer is a common malignant tumor of digestive tract, and is in the second place of gastroenteric tumors. The predilection sites are rectum and the junction between rectum and sigmoid colon, which account for 60%. With changes of people's life style and dietary pattern, there is a tendency that morbidity and mortality of colorectal cancer rise year by year. The disease mostly occurs at the age of 40 afterward, and the ratio of male to female is 2:1. Currently, the method of early diagnosis of colorectal cancer comprises Fecal occult blood test (FOBT), Colonoscopy, stool DNA mutation detection and stool RNA-specific gene detection and so on, and Double-contrast barium enema (DCBE), etc. Colonoscopy is considered as a golden standard for diagnosing colorectal cancer. However, as it is an invasive examination, it requires intestinal tract preparation. During the examination, there are risks of occurring complications such as bleeding and perforation, so patient acceptance is not good and the cost is relatively high. Although fecal occult blood test is not an invasive detection, the examination results are susceptible to factors such as diets and the sensitivity and specificity of fecal occult blood test are not satisfactory as to screening of colorectal cancer.
Mature microRNAs (miRNAs) area class of single-stranded RNAs, each of which does not encode proteins and consists of 18 to 24 bases. Binding of a mature microRNA to corresponding mRNA results in degradation or silence of the mRNA, and then regulation of gene(s). Researches in recent years show that specific expression of miRNA is associated with development and progression of tumors, and some miRNAs can even play a role of anti-oncogenes or oncogenes. Cyclooxygenase (COX) is an important rate-limiting enzyme in the process of prostaglandin synthesis. COX2 is not expressed in a normal tissue, but may be expressed inducibly by the action of various stimulating factors. Thus, it is also called inductive early responsive gene which is closely related to development and progression of tumors. It is discovered in researches in recent years that COX2 is over-expressed in most head and neck tumors and that COX2 is also one of the biomarks for colon cancer. Therefore, if a corresponding colon cancer kit can be developed so that the kit can be applied in the field of scientific researches, the researches on colon cancer screening and transformation of scientific research achievements would be greatly accelerated, which necessarily plays a significant role in promoting diagnosis and treatment of colon cancer.